Optional decks are special secondary decks, usually placed in the command zone, that are allowed to be played in addition to a player's main deck. Optional decks do not count as part of a player's sideboard.
Optional decks include:
- Attraction deck (acorn)
- Contraption deck (acorn)
- Planar deck, which is optional for players but required for the Planechase format.
The ten sticker sheets a player in Constructed acts somewhat like an optional deck, as they deal out three sheets at random at the beginning of each game. However, unlike those above, it is not interacted with again for that game.